摘要
Positron lifetime and Doppler Broadening spectra have been measured for three types of GaAs semiconductors. Direct evidence of native vacancy-type defects is found in the semi--insulating (SI-type) and n-type sample as its average lifetime Tin and S-parameter are larger than the bulk value. No positron trapping occurred in p-type GaAs. The lifetime spectrum of n-GaAs has also been measured as a function of temperature. The increase in average lifetime τm from 226 ps to 234 ps at the temperature range 95-330 K was observed and was explained by the ionization of the vacancy. The slight increase in bulk lifetime τb with the temperature was caused by the latticeexpansion and expansion coefficient α=14×10-6-1 was evaluated.
Positron lifetime and Doppler Broadening spectra have been measured for three types of GaAs semiconductors. Direct evidence of native vacancy-type defects is found in the semi--insulating (SI-type) and n-type sample as its average lifetime Tin and S-parameter are larger than the bulk value. No positron trapping occurred in p-type GaAs. The lifetime spectrum of n-GaAs has also been measured as a function of temperature. The increase in average lifetime τm from 226 ps to 234 ps at the temperature range 95-330 K was observed and was explained by the ionization of the vacancy. The slight increase in bulk lifetime τb with the temperature was caused by the latticeexpansion and expansion coefficient α=14×10-6-1 was evaluated.
